Process of removing injurious ingredients from petroleum distillates



Patented Dec. 5, 1933 PROCESS OF BEMOVIN INJURIOUS INGRE- DIENTS FRGM PETROLEUM DISTILLATES William Alvah Smith, Hamburg, N. Y.

No Drawing. Application September 18, 1929 Serial No. 393,585

6 Claims.

This invention relates to methods of removing objectionable sulphur, whether in combined or uncombined condition, from petroleum distillates.

Heretofore, sulphur has generally been removed from petroleum distillates by a treatment of the distillate by concentrated sulphuric acid which has a property of dissolving the sulphur compounds, as in the so-called acid-lye-litharge process. The acid with the sulphur compounds dissolved therein is then removed from the distillate in the form of a sludge which is difiicult to dispose of. The main objection, however, to the treatment of distillates with sulphuric acid is that the sulphuric acidpolymerizes and removes some of the unsaturated hydrocarbon compounds in the distillate, which compounds are very desirable in an unpolymerized state for the reason that they reduce the tendency of gasoline to knock? when used in an internal combustion engine. Another objection ,to the use of sulphuric acid method is that certain sulphur compounds are not removed from the dis"- oils, after treatment with sulphuric acid acquire very objectionable odors caused by the formation of certain sulphur, compounds whichare not removed from the distillate by the acid-lye-litharge treatment. l

Attempts have also been made to remove 'sulphur and sulphur compounds from petroleum distillates by meansof certain metals, oxides or salts of metals, but such attemptshavehot been Further objects of this invention are to pro vide aprocess ofv this'kind by means of which sulphur compounds which are not removed by the usual acid-lye-litharge' treatment may be readily removed from the distillate by changing the same into other sulphur compounds which are either entirely or' mainly insoluble in the distillate or into compounds which are not objectionable; also to provide a process of this kind -by means of which sulphur is removed from distillates by the'use of certain copper and zinc compounds which react with the sulphur compounds to form sulphides or other insoluble or slightly soluble sulphur compounds which can be readily removed from the distillate, or which 30 react with the sulphur compounds to form compounds which are more readily removed from the distillate by ordinary refining methods; and also to improve methods of this kind in other respects hereinafter specified.

. In accordance with my process, the distillate may be treatedbefore or after the usual acidlye-li'tharge treatment which removes the greater portion of the sulphur compounds, or before or after any other process, such as for example the 7 sodium hypochlorite process, or the liquid sulphur dioxide process, but preferably my ,process is to be used in place of these other processes or treatments, in order to produce a distillategin which the unsaturated hydrocarbons are not 7 f polymerized.

g In carrying out my process thedistillate is subjected to the action of certain copper or zinc tillate by the sulphuric acid, 50 that some crude compounds, or both, this being preferably done while the distillate is at atmospheric tempera- 30 ture. and by thoroughly mixing a copper or zinc compound or compounds in finely divided form withthe distillate. Reaction takes place between the sulphur compounds in the distillate and the copperorzinc compounds resulting in 5 the formation of sulphur compounds which are eitherentirely insoluble in the distillate or else soluble only to a slightextent, or in a soluble form which is not objectionable, .or readilyremovable from the distillate by ordinary refining methods.v These ,insoluble compounds can then be removed.inany'suitable or usualmanner, for example, byprecipitation, centrifuging-or if desired, by redistilling the distillate thus treated. The insoluble sulphurcompounds formed during thereaction can be conveniently removed from the distillatefby meahs,of an adsorbent material suchas 'fullers earth, silica gel and the like or by filtration, distillation,.etc.

I have found that certain copper and zinc ,compounds are desirable for usein the removal of sulphur compounds from distillates, and also that other copper compounds ,willefiectively remove thesesulphur compounds but willreplace I the same with compounds that arev injurious to 5 internal combustion engines when the distillate is ,usedas amotor fuel. For examp'le,.certain compounds of copper and chlorine very effectively changethe sulphur compounds in the distillate into substantially insoluble compounds which can be readily removed from the distillate. However, the chlorine forms certain chlorine compounds which cannot readily be removed from the distillate and which, during the use of the distiilate as a motor fuel, forms an acid, acids or compounds which have a harmful action on the engine or other parts of th mechanism. r

I have also found that many copper compounds, such as the oxides of copper, the sulphur compounds of copper, and others, are not effective in removing all or" the objectionable sulphur compounds, so that by using such compounds, either no sulphur or only a part of the sulphur content of the distillate desired to be removed is removed, which renders these materials undesirable for use in producing a motor fuel.

I have found that in order to produce a distillate which is practically free from objectionable sulphur and also usable as a motor fuel without injury to or detrimental action on the motor, certain copper and zinc compounds, particularly the nitrates and silicates, are very efiective in the removal of the objectionable sulphur.

Examples of such compounds are copper nitrate, copper silicate, zinc silicate, and others.

In the use of these copper and zinc compounds, I have found that considerable moisture, even in the form of water of crystallization is a deterrent factor. For instance, very damp copper silicate sometimes produces a distillate which is badly off color, even though the distillate was practically colorless before treatment, but the same copper silicate after drying at a suitable temperature produces a practically colorless distillate, that is, the distillate does not change color because of this treatment. Copper silicate and zinc silicate are particularly useful in the removal of mercaptan compounds, and in combination with relatively small amounts of dry copper nitrate in the removal of sulphides and disulphides, or their conversion into unobjectionable forms. In the case of the removal of sulphides and disulphides, copper nitrate has been found'very effective, particularly if it is ground in intimate contact with some water absorbing material, such as, anhydrous calcium chloride to eliminate the water of crystallization and so produce what is essentially anhydrous copper nitrate. In some cases the use of a small amount of zinccompound, such as, silicate accelerates the action of the copper compound.

I have also found that heating greatly facilitates the progress of the reaction, in some cases reactions which require several hours at room temperature are completed in very much less time at higher temperatures. In my work, I have used temperatures up to 450 centigrade in closed vessels. However, elevated temperatures are not necessary if the proper amount of time is available for the treatment.

After the reaction between the objectionable sulphur compounds, and the copper or zinc compounds has been completed, the newly formed sulphur compounds together with any of the copper or zinc compounds remaining in the distillate, are removed from the distillate in any suitable manner and the. precipitate thus removed may be reactivated. If desired, a part of the precipitate may be retained in the reaction vessel and used again, and the precipitate which is removed is then preferably dried by heating to vaporize the distillate mixed therein which may then be condensed and recovered. The precipitate can be washed with water, either hot or cold, to remove the portion thereof which is water soluble, which may then be converted into copper or zinc hydroxide by adding caustic soda to the water, the copper hydroxide being precipitated or reactivated in any other efiective manner. The remaining portion of the precipitate, or if desired, all of the precipitate may be washed with an acid such as nitric acid, which dissolves the copper compounds and enables them to be reconverted into useful copper ccmpoun s by suitable treatment. For example, if the material thus formed is treated with caustic soda, copper hydroxide will be formed,

or if treated with sodium carbonate solution basic copper carbonate will be formed. The nitrate form may be used directly to remove sulphur compounds for distillates. The fact that the material used in the reaction can be recovered and used again renders the process described feasible and less expensive to carry out. If desired, the precipitate, either in part or wholly, may be treated in any other desired manner to recover desired or valuable constituents. V

In removing the precipitate from the treated distillate, some of the distillate is retained.

This retained liquid may be recovered by heating the precipitate and condensing the vapor, or the liquid may be removed by centrifugal or other means. Consequently, there is practically no loss of the distillate during the treatment of the same by my improved process.

When the copper or zinc compounds are brought into contact with the distillate, only the objectionable sulphur compounds are acted upon and there is consequently no change in the distiliate and unsaturated materials in the distillate are not polymerized. Hence, the anti-knock qualities of the unsaturated hydrocarbons are not affected by my improved process, as is the case when the distillate is treated with sulphuric acid in the ordinary acid-lye-litharge treatment. When distillates are treated inaccordance' with the acid-lye-litharge process, a very considerable loss of distillate occurs, this loss being due to foo ifs

thedistillate whichis contained in the sludge M which is formed during this treatment.

The acid-lye-litharge process is frequently not carried to completion because of the cost of the complete treatment. My process may be used as an adjunct to the acid-lye-litharge treatment,

causing the removal of sulphur or objectionable compounds not removed by the acid-lye-litharge process. Also in carrying out the acid-lyelitharge process, a certain amount of elemental sulphur is usually added to facilitate the reaction. The elemental sulphur dissolves to a certainextent in the distillate and is practically never removed therefrom. My process avoids the use of elemental sulphur, which has the property of dissolving to a certain extent in the distillate.

My process is applicable to all sorts of petroleum distillates and is particularly useful in removing sulphur from distillates which do not readily yield to the older methods of treatment, and very little skill is required to carry out my process. The treated distillate is negative to the Doctor test, and negative to the copper'strip corrosion test, and is frequently marketable without redistillation, or. removal of the reaction products.

I claim:

1. The process of desulphurizing petroleum distillates, without materially decreasing the antiknock properties thereof, which comprises contacting the distillate with a mixture of copper silicate and zinc silicate.

2. The process of desulphurizing petroleum distillates, without materially decreasing the anti-knock properties thereof, which comprises contacting the distillate with -a mixture of dry particles of copper silicate, zinc silicate, and copper nitrate.

3. The process of desulphurizing petroleum distillates, without materially decreasingthe antiknock properties thereof, which comprises contacting the distillate with copper silicate and a relatively small amount of a zinc compound.

4. The process of desulphurizing petroleum distillates, without materially decreasing the antiknock properties thereof, which comprises contacting the distillate with a major amount of copper silicate, a relatively small amount of a Zinc compound and a small amount of dry copper nitrate.

5. The process of desulphurizing petroleum distillates, without materially decreasing the anti-knock properties thereof, which comprises contacting the distillate with copper silicate and a relatively small amount of zinc silicate.

6. The process of desulphurizing petroleum distillates, without materially decreasing the anti-knock properties thereof, which comprises contacting the distillate with copper silicate, zinc silicate, and copper nitrate under approximately anhydrous conditions.

WILLIAM ALVAH SMITH. 

